title: Dissecting the thermodynamics of GAP-RhoA interactions.
abstract: We describe a detailed study of the RhoA-binding epitope of the GAP domain of Graf, including the determination of the thermodynamic and kinetic parameters of the interaction of wild-type domain, and of its 15 single-site mutants, with cognate GTPases. We show that residues important for the structural integrity of the Arg-finger loop are critical for binding Rho and for the catalytic activity of GAP, but GTPase selectivity appears to be modulated by a much more subtle interplay of electrostatic and hydrophobic interactions involving residues on the periphery of the main interface. The eight residues targeted in this study are involved in three distinct patches on the surface, two of which appear to interact with highly conserved regions of the GTPase, while the third plays a role in GTPase selectivity.
authors.affiliation: Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Tamka 2, 50-137 Wroclaw, Poland.
authors.forename: Filip
authors.initials: F
authors.lastname: Jelen
authors.forename: Pawel
authors.initials: P
authors.lastname: Lachowicz
authors.forename: Wlodzimierz
authors.initials: W
authors.lastname: Apostoluk
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Mateja
authors.forename: Zygmunt S
authors.initials: ZS
authors.lastname: Derewenda
authors.forename: Jacek
authors.initials: J
authors.lastname: Otlewski
mesh_terms: D000595:Amino Acid Sequence; D020690:GTPase-Activating Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D013816:Thermodynamics; D020742:rhoA GTP-Binding Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: C115971:ARHGAP26 protein, human; D020690:GTPase-Activating Proteins; C066737:RHOA protein, human; D006160:Guanosine Triphosphate; D020742:rhoA GTP-Binding Protein